This invention relates to pipe thawing apparatuses, and more particularly to a pipe thawing apparatus that thaws a pipe by directing a stream of hot water into the pipe against ice in the pipe to melt the ice.
Frozen pipes and how to thaw them are problems encountered every winter in areas where temperatures drop below freezing. Until relatively recently, pipes have been made of metal and could be thawed by passing an electric current through them or by heating the pipes with a torch. However, plastic pipes, which are being used with increasing frequency in recent years, cannot be thawed by using either technique.
Apparatuses and techniques have been developed for thawing frozen plastic pipes. One technique is to break open the pipe and direct a stream of heated water into the pipe, to thaw the ice. This is done by advancing a flexible tube through the pipe and directing a stream of heated water through the tube. By advancing the flexible tube through the pipe, the outlet of the flexible tube is placed in close proximity to the ice in the pipe so that the heated water exiting the tube is immediately directed against the ice. Apparatuses utilizing this technique are disclosed in U.S. Pat. No. 4,124,039 to St. Laurent for a pipe thawing machine and in U.S. Pat. No. 4,250,925 to Mast for a pipe unfreezer.
Both the Mast device and the St. Laurent device are closed systems. That is, a return line is coupled to the pipe to be thawed and the flexible tubing inserted into the pipe through the return line. Water is thus recirculated from a source of hot water in the devices, through the feed tube into the pipe, and then back through the return line into the devices to be reheated. Since the system is closed, this avoids introducing contaminants into the pipe which is desirable since in many cases the pipes to be unthawed carry drinking water.
A problem which devices of this type must overcome is that the path the flexible tubing must follow in the pipe can be tortuous. The pipe may bend at angles, which in many cases are ninety degree angles, and there may frequently be junctions where pipes branch off from each other. Consequently, the tip of the flexible tubing may be provided with some type of guiding apparatus to facilitate the feeding of the flexible tubing through the pipe. For example, the flexible tubing or feed tube 16 shown in Mast has a distal or probing end that has a tip provided with elongate side expanses 28a, 28b, 28c, that are formed by cutting the sides of the feed tube to remove material whereby tapered fingers are left which form the expanses. Since the fingers are tapered, and unjoined from each other, they have a greater degree of pliancy than the feed tube 16 proper. When such a tip is advanced through a pipe, the fingers yieldably guide the tip around corners and other obstructions.
Another problem encountered with such devices is that when heated water is supplied in a steady stream to the pipe, a pressure head builds up. This pressure head tends to force the flexible feed tube back out of the pipe. This makes it more difficult to feed the flexible feed tube through the pipe.
It is an object of this invention to provide an apparatus for thawing pipes by advancing a flexible feed tube through the pipe and directing a pulsating stream of heated water through the flexible feed tube into the pipe.
It is another object of this invention to provide an apparatus where the stream of heated water can be selectively supplied as a continuous stream or a pulsating stream.
It is another object of this invention to provide an improved tip for a flexible feed tube used with an apparatus for thawing pipe that directs water into the pipe through the flexible feed tube to facilitate the advancement of the flexible feed tube through the pipe.